ILE4278

June, 2013, Rev. 02

The watchdog output can be used as an interrupt signal for the microcontroller. In any

case it is possible to connect pin WO and pin RO externally.

When the controller is set to sleep mode or low power mode its current consumption

drops and no watchdog pulses are created. In order to avoid unnecessary wake up

signals due to missing pulses at pin WI the watchdog feature can be disabled as a

function of the load current. The switch off threshold is set by an external resistor to pin

WADJ. The watchdog function can also be used as a timer, which periodically wakes

up the controller. Therefore the pin WADJ has to be connected to the output Q.

The power on reset feature is necessary for a defined start of the microprocessor when

switching on the application. The reset signal at pin RO goes high after a certain delay

timed

The delay time is set by the external delay capacitor. An under voltage reset circuit

supervises the output voltage. In case

output is set to LOW after a short reset reaction time

generated down to an output voltage

threshold can be adjusted by an external voltage divider. This feature is useful with

microprocessors which guarantee a safe operation down to voltages below the

internally set reset threshold of 4.65 V typical.